Potential For Population Regulation Of The Zebra Mussel By Finfish And The Blue Crab In North American Estuaries

We conducted a series of descriptive and manipulative experiments aimed at quantifying the abundance, natural mortality, and effectiveness of predators in controlling the zebra mussel, Dreissena polymorpha, in the Hudson River Estuary. First, we measured distribution, abundance, and mortality rates of a zebra mussel population in the middle portion of the Hudson River Estuary, NY. Rocks were collected along a depth gradient in the field and sampled for the density and size structure of the resident mussels over the growth season. Next, we either allowed access (controls) or denied access (predator exclusion) to predators in field experiments with rocks harboring a known number of zebra mussels to estimate natural mortality. Finally, we conducted manipulative field experiments to test the effectiveness of the blue crab, Callinectes sapidus, at consuming zebra mussels by presenting similar rocks to crabs in field enclosures. Field sampling in June, July, and August 1993 indicated a dense (similar to 30,000 mussels/m(2)) population composed of a single cohort of 1 + year-class mussels. Sampling in August 1994 indicated a decline in D. polymorpha density. Mussel density increased dramatically with depth less than 2 m below the spring low tide mark. in cage experiments, blue crabs caused mortality rates that were an order of magnitude higher than those measured for the local predator guild, which was primarily composed of finfish. Localized extinctions of zebra mussels within one growth season were predicted in areas where blue crab densities approach 0.1 crabs/m(2)

Evaluations of Hawaii Creole English and standard English

The growing number of multicultural dialect and creole speakers entering the public school system underlines the importance of understanding perceptions pertaining to language standards and differences. Previous research has shown a consistent evaluative difference between nonstandard and standard linguistic forms. In this study, 197 university students were randomly assigned to rate an audio tape delivered in Hawaii Creole English or Standard English. Results were similar to previous studies in that the speaker’s language had a significant impact on the listeners’ ratings. Listeners rated Standard English higher on superiority traits and quality of speech. However, Hawaii Creole English was favored on dynamism traits. Furthermore, listeners’ own ethnicity and language ability influenced their ratings on quality, attractiveness, and dynamism. Findings have implications for educational programs designed to teach English and for the broad multicultural population